diff mbox series

[net-next,v5,2/4] vsock/virtio: support to send non-linear skb

Message ID 20230730085905.3420811-3-AVKrasnov@sberdevices.ru (mailing list archive)
State Changes Requested
Delegated to: Netdev Maintainers
Headers show
Series vsock/virtio/vhost: MSG_ZEROCOPY preparations | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1328 this patch: 1328
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 1351 this patch: 1351
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1351 this patch: 1351
netdev/checkpatch warning WARNING: line length of 86 exceeds 80 columns WARNING: line length of 87 exceeds 80 columns WARNING: line length of 88 exceeds 80 columns WARNING: line length of 91 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Arseniy Krasnov July 30, 2023, 8:59 a.m. UTC 
For non-linear skb use its pages from fragment array as buffers in
virtio tx queue. These pages are already pinned by 'get_user_pages()'
during such skb creation.

Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
---
 Changelog:
 v2 -> v3:
  * Comment about 'page_to_virt()' is updated. I don't remove R-b,
    as this change is quiet small I guess.

 net/vmw_vsock/virtio_transport.c | 41 +++++++++++++++++++++++++++-----
 1 file changed, 35 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index e95df847176b..7bbcc8093e51 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -100,7 +100,9 @@  virtio_transport_send_pkt_work(struct work_struct *work)
 	vq = vsock->vqs[VSOCK_VQ_TX];
 
 	for (;;) {
-		struct scatterlist hdr, buf, *sgs[2];
+		/* +1 is for packet header. */
+		struct scatterlist *sgs[MAX_SKB_FRAGS + 1];
+		struct scatterlist bufs[MAX_SKB_FRAGS + 1];
 		int ret, in_sg = 0, out_sg = 0;
 		struct sk_buff *skb;
 		bool reply;
@@ -111,12 +113,39 @@  virtio_transport_send_pkt_work(struct work_struct *work)
 
 		virtio_transport_deliver_tap_pkt(skb);
 		reply = virtio_vsock_skb_reply(skb);
+		sg_init_one(&bufs[out_sg], virtio_vsock_hdr(skb),
+			    sizeof(*virtio_vsock_hdr(skb)));
+		sgs[out_sg] = &bufs[out_sg];
+		out_sg++;
+
+		if (!skb_is_nonlinear(skb)) {
+			if (skb->len > 0) {
+				sg_init_one(&bufs[out_sg], skb->data, skb->len);
+				sgs[out_sg] = &bufs[out_sg];
+				out_sg++;
+			}
+		} else {
+			struct skb_shared_info *si;
+			int i;
+
+			si = skb_shinfo(skb);
+
+			for (i = 0; i < si->nr_frags; i++) {
+				skb_frag_t *skb_frag = &si->frags[i];
+				void *va;
 
-		sg_init_one(&hdr, virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb)));
-		sgs[out_sg++] = &hdr;
-		if (skb->len > 0) {
-			sg_init_one(&buf, skb->data, skb->len);
-			sgs[out_sg++] = &buf;
+				/* We will use 'page_to_virt()' for the userspace page
+				 * here, because virtio or dma-mapping layers will call
+				 * 'virt_to_phys()' later to fill the buffer descriptor.
+				 * We don't touch memory at "virtual" address of this page.
+				 */
+				va = page_to_virt(skb_frag->bv_page);
+				sg_init_one(&bufs[out_sg],
+					    va + skb_frag->bv_offset,
+					    skb_frag->bv_len);
+				sgs[out_sg] = &bufs[out_sg];
+				out_sg++;
+			}
 		}
 
 		ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL);